Hopsitial Acquired Infections Of The Respiratory System Flashcards
When are hospital inquired infections the most common in the hospital setting
When a patient is already immunosupression
When a patient is using a ventilator
What bacterium is most common in hospitals due to the oral flora shifting in hospital admissions?
S. Aureus
Pseudomonas
Klebsiella
Acinetobacter
Strep pneumonia
GAS
Most common associated risks with ventilation assistance
Pneumonia
Pulmonary edema
Acute respiratory distress syndrome (ARDS)
How to infections in ventilation most commonly occur?
With ventilation via tubes, normal cilia clearance of bronchial secretions is immobilized
- also biofilms form easily on tubing and usually within 1 day of placement
Are hospital acquired pneumonia more likely to be bacterial or viral
Bacterial (75%)
Other 25% is viral
Aspergillus fumigatus
Opportunistic fungal pathogen in HIV and immunocompromised patients
- causes necrotizing diseases
Invasive vs non-invasive aspergillus
Invasive
- has invaded tissues and looks singular
- requires grocotts methenamine silver staining (GMSS)
Non-invasive
- has not invaded tissues and looks clumped up together
- also requires GMSS
Both types of spores look like “fruiting heads” in microscope slides
Conidia
Spores of aspergillus that are inhaled and then infect if the patient cant combat it
the stalk is called conidiophores
Acute pulmonary aspergillosis
Disease that forms via aspergillus infections
- most common cause of death associated with aspergillus
Granulomas become invasive and systemic causing the following
- fever
- increased ESR
- chest pain
- coughing
- eventually moves to brain and kills if untreated
stem cell transplant patients have increased risk (idiopathic)
Pulmonary aspergilloma
Non-invasive aspergillosis infection
Requires surgery to remove and usually doesnt kill
- often asymptomatic
Often forms due to history of cavitation lung diseases which includes
- TB
- emphysema
- valley fever
- sarcoidosis
- Is only dangerous if the aspergilloma is stupid big or breaks off*
- however treatment should be initiated once diagnosed, regardless of size
Allergic bronchopneumonia aspergillosis
Aspergillosis infection that idiopathically induces an IgE-mediated type 1 hypersensitivity
More common in asthmatic and CF patients
- presents like allergic asthma with very bad wheezing (distinguished when looking at CT and Xrays)
Acinetobacter Baumannii
Aerobic gram(-) coccobacillus
Super rare but does appear in hospital induced infections
- survives for weeks on hospital surfaces
Super swift acquisition of antibiotic resistance
- highest rate of resistance among all gram (-) bacteria
- lots of efflux pumps and B-lactams ECs
- also very high rates of mutating targets
Grows only on macconkey agar
- then use PCR afterwards
Tests:
- catalase (+)
- lactase (+)
- Oxidase (-)
- B-lactam (+)
How do biofilms differ between acinetobacter and pseudomonas?
Pseudomonas always mass produces biofilms with ease, but it does not last long and is easy to kill (as long as you know about it)
Acinetobacter produces less biofilms masses, but lasts really long and can kill easier
Nocardia
Genus of a rare bacterium that occasionally produces outbreaks
- two most common are
1) N. Asteroides (causes pulmonary issues)
2) N. Brasiliensis (causes cutaneous issues)
All are gram (+) filament rod but only stains as acid-fast
- when growing on agar, looks like “molar teeth” and fuzzy colonies (possess aerial hyphae)
Tests:
- catalase (+)
- superoxide dismutase (+)
Virulence factors
- superoxide dismutase = allows it to break down ROS in macrophages
- cord factor = prevents phagosomes-lysosome fusion (similar to TB)
Two bacterial species that have cord factor as a virulence factor
Nocardia species
TB species
